Electron holes in a κ distribution background with singularities

Abstract

The pseudo-potential method is applied to derive diverse propagating electron–hole structures in a nonthermal or κ particle distribution function background. The associated distribution function Ansatz reproduces the Schamel distribution of [H. Schamel, Phys. Plasmas 22, 042301 (2015)] in the Maxwellian (j ! 1) limit, providing a significant generalization of it for plasmas where superthermal electrons are ubiquitous, such as space plasmas. The pseudo-potential and the nonlinear dispersion relation are evaluated. The role of the spectral index κ on the nonlinear dispersion relation is investigated, in what concerns the wave amplitude, for instance. The energy-like first integral from Poisson’s equation is applied to analyze the properties of diverse classes of solutions: with the absence of trapped electrons, with a non analytic distribution of trapped electrons, or with a surplus of trapped electrons. Special attention is, therefore, paid to the non-orthodox case where the electrons distribution function exhibits strong singularities, being discontinuous or non-analytic.